It is known as disclosed in U.S. Pat. Nos. 4,325,431, 4,454,913; and copending patent application Ser. No. 789,234 filed Oct. 18, 1985, and owned by the assignee of the present application, to use a hydraulically actuated equalizing valve for equalizing the pressure above and below a subsurface safety valve prior to opening the safety valve. While this protects the main valve in the subsurface safety valve, the equalizing valve is subject to failure as a result of erosion and flow cutting of the equalizing valve element and seat and the equalizing valve element is subject to damage when various well treatment processes, such as well fracturing operations, are performed in the well.
The present invention is directed to a subsurface safety valve having an equalizing passageway or line and valve in which an additional valve is provided, which is normally opened, to be closed to protect the equalizing valve. Such a valve increases the life and dependability of the equalizing valve and provides a means for allowing the safety valve to fully shut off well production flow and thus perform its intended function even in the event that the equalizing valve fails.